<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>选择器</title>
    <style>
        /*元素选择器*/
        div{
            background: blueviolet;

        }
        /*类选择器*/
        .d1{
            background: blue;
        }
        /*ID选择器*/
        #d2{
            background: red;
        }
        #d3{
            background: pink;
        }
        /*通用选择器*/
        *{
            font-size: 20px;
        }
    </style>
</head>
<body>
    <div>元素选择器</div>

    <div class="d1">类选择器</div>
    <div class="d1">类选择器</div>

    <div id="d2">ID选择器</div>
    <div id="d3">ID选择器</div>
</body>
</html>